Relay system



Jan. .25, 1927.

F. M. BILLHIMER RELAY SYSTEM Filed June 5, 1920 AAAAA' INVENTOR flan/r MB/fl/I/mer WITNESSES: X @W ATTORNEY Patented Jan. 25, 1927.

UNITED STATES PATENT OFFICE.

FRANK M. BILLHIMER, F WILKINSBURG, PENNSYLVANIA, ASSIGNOR T0 WESTING- HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- VANIA.

RELAY Application filed June 3.

My invention relates to relay systems and particularly to load-limiting relay systems.

One object of my invention is to provide means for disconnecting a distributmg circuitfrom a source of energy when the power demand upon the distributing circuit exceeds a predetermined value for a predetermined interval of time. I

Another object of my invention is toprovide a relay system, of the above-indicated character, that shall be simple and reliable in its operation. 1 c

In practicing my invention, I provide an overload relay, a thermal relay and an un derload relay which co-operate to trip an interrupter when an amount of energy equal to or exceeding a predetermined value traverses the interrupter for a predetermined interval of time. While current below the full-load value traverses the interrupter, only the under-load and the overload relays are energized from the current transformer in the distributing circuit. When the currentthat traverses the interrupter attains or exceeds a predetermined value, as, for example, 100% full load, the overload relay is actuated to include the thermal relay in circuit with the current transformer by means of auxiliary contact members that are controlled by the overload relay. If the overload obtains for a predetermined interval of time, the thermal relay will actuate its contacts to complete a circuit for tripping the interrupter. The interval of time required for the operation of the thermal relay varies inversely with the overload on the circuit.

The single figure of the accompanying drawing is a diagrammatic view of a relay system embodyingmy invention.

A distributing circuit 1 is adapted to receive energy from a source 2 of electromotive force through a circuit interrupter An auxiliary relay circuit for controlling the tripping of the interrupter 3 comprises a current transformer 4, an underload relay 5, an overload relay 6 and a thermal relay 7. The operation of the relays, according to predetermined conditions, completes a circuit whereby a tripping magnet 8 of the in terrupter 3 is energized, from a source 9 of electromotive force, to trip the interrupter.

The underload relay comprises a magnetizable core member 10 having an energizing winding 11 therefor, a rotatively movable member 12 and a pair of contacts 13 SYSTEM.

1920. Serial No. 386,404.

one of which is operated by the member 12 of the relay. The overload relay 6 is of solenoid type and comprises a movable mag netizable member 14, an energizing winding 15 therefor and a plurality of stationary con tact members 16, 17, 1.8 and 19 that are adapted to be engaged by corresponding movable bridging contact members 16, 17, 18 and 19. The thermal relay 7 comprises a thermal-storage means 20, a heating winding 21, and a plurality ofcontact members 22 engagement of which by a bridging contact member 22 is eflected when the relay 7 is heated to a predetermined degree.

When the value of the current that traverses the circuit is less than that of full-load current, a circuit obtains from one terminal of the current transformer 44, through the winding 11 of the relay 5, the winding 15 and the contact members 19 and 19 of the relay 6, to the other terminal of the current transformers 4. This causes the contact members 13 of the relay 5, one of which is connected to One of the contact members 17, and the other of which is connected to one of the contact members of each of the pairs 18 and 19, to engage. The circuit of the winding 21 of the relay 7 is controlled by the contact members 18 and 18 of the rela 6. hen the circuit current attains fullbad value, the contact members of the relay 5 are disengaged by the movement of the movable member 12, and the member 14 of the relay 6 is likewise actuated, whereby the respective pairs of contact members 16, 17 and 18 are connected together by the correspond ing bridging members 16, 17 and 18 and the bridging contact member 19 is disconnected from the contact members 19. Upon the actuation of the relay 6, a circuit is completed from one terminal of the current transformer 4, through the winding 11 of the relay 5, the winding 15, the contact members 18 and 18 of the relay 6 and the winding 21 of the relay 7, to the other terminal of the current transformer 4. The actuation of the relay 6 thus serves to introduce the relay 7 into the circuit of the current transformer 4.

If the current that traverses the circuit is maintained at a value in excess of full load, the relay 7 becomes heated in accordance with such excess value. lVhen the relay 7 becomes heated to a predetermined degree, its contact members 22 are connected rupter for the circuit, of means responsive to the current in the circuit and co-operating thermal means for actuating the interrupter under predetermined conditions, and means responsive to a predetermined value of current for rendering the current-responsive means and the thermal means inoperative for actuating the interrupter.

8. In a load-limiting device for an electric circuit, the combination with an interrupter for the circuit, of means responsive to the current in the circuit and co-operating thermal means for actuating the interrupter under predetermined conditions, and means responsive to a predetermined minimum value of current for controlling the interrupter-actuating means.

9. A load-limiting device for an electric circuit comprising means responsive to and traversed by the current in the circuit, means having a time element varying inversely as the current in the circuit varies, and means responsive to a predetermined minimum value of current for controlling the currentresponsive means and the time-limit means.

In testimony whereof, I have hereunto subscribed my name this 27th day of May, 1920.

FRANK M. BILLHIMER. 

